Electric incandescent lamp.



PATENTED MAR. 6, 1906.

W. J. PHELPS. ELECTRIC INGANDESGBNT LAMP.

APPLICATION FILED DEOJZZ, 1902.

Jllzhedded: I

V H 'L. (BMW UNITEDT s'rA'rEs PATENT OFFICE.

WILLIAM J. Pi ELPs, OF DETROIT, MICHIGAN, ELECTRIC INCANZDESCENT LAMP.

No.,814,1t32.

Specification of Letters Patent.

Patented March 6, 1906.

Application filed December 22, 1902. Serial No. 136,160.

To all whom it may concern: V

Be it known that I, WILLIAM J. PHELPS, a citizen of the United States,and a resident of the city of Detroit, county of Wayne, and

'State of Michi an, have invented certain filaments designed to emitlight of varying intensity such as described in prior Letters Patent ofthe United Statesgranted to me, No. 603,705, May-10, 1898.

The present improvement seeks to provide an effective arrangement of theseparate filaments within the lamp which Wlll prevent short-circuitingbetween them and which will allow the employment of filaments of highefficiency, but prevent them from droopmg. A fprther object is toimprove the arran ement, of the leading-in wires, which Will acilitatethe manufacture and, in particular, the exhausting of the lamp. I

The invention consists in the features of construction and arrangementof parts set forth the following description, illustrated in theaccompanying drawings, and more particularly pointed out in the appendedclaims. In the drawings, Figure lis a side elevation of the improvedform of lamp." Fig. 2 is I an elevation taken at an an 1e to the view,shown in Fig; 1 and" with t e base of the lam in section. T e base ofthe lamp may be of anywellknown or desired t e and adaptedto be usedwith any suitab e form of lamp-holder. .To illustrate the presentimprovement, the Edison type of lamp-base is shown, which com rises ascrew-shell 10; which forms one of t e lamp-terminals for the receptionof current from the lamp-holder and which support within its outer endthe glassivacuumulb' 11, held in position by suitable compositionfilling v12. Aninsulating disk 13, of porcelain or other suitablematerial, mounted within the. inner end of screw-shell, carries 'acentral contact in the form of a tubular,

uni n14, which passes through a central openm in the disk and is flanged*at either end to hold it securely in position. A bent springmetal piece15 is clamped to the face of disk 13 ,by the upper flanged end of thetubular rivet '14, but is insulated from the latter by a suitable washer16. The metal piece 15 forms the second terminal of the lam and engagesthe central terminal of the ampho der for the reception of currenttherefrom. As shown, the upper end of the lamp-terminal 15 extends aboveand normally out of engagement with the contact 14, but may be depressedinto engagement with such contact y any suitable meansas, for example,when the lamp is secured completely intp its holder.

Preferably two filaments 17 and 18 of different candle-power areemployed within the vacuum-bulb 1 1 the large or high-power fila- -mentbeing arranged-belowthe small or low power filament 18. The filamentsare con- .nected to lamp-terminal 15 by leadingin "wire 22, while thejoined ends of the filaments are connected to the contact 1 This =latterconnection is preferably formed of two leading-inwires 23 and 24,twisted together and connected, respectively, to the filaments 17 and 18for the purpose hereinafter stated.

The lamp is designed for use with an elecstant potential, and preferablythe large or high-power filament 17 is 'of lower resistance er unit oflength than the small low-power filament 18. If the current is caused toflow from lam -terminal 15-to lamp-terminal 10, as Whent e lamp isscrewed partially to its holder, the current will flow through bothfilaments in series, and filament 18 willalone glow with, for example,one-candle power, while filament 17 will act as a relatively dark anddead resistance, cutting down the amount of current used. When, however,springterminal 15 is depressed into engagement with contact 14, as whenthe lamp is screwed completely into its holder, filament 18 will beshort circuited, and the current will flow through filament 17 alone,which will glow with the full candle-power of the lamp-for example,sixteen-candle power. The parts thus far described may be widely variedwithout departure from the essentials of the present invention. andterminals may be adapted to any suitable lamp-holder, and themodification of the flow of current to the separate filaments may beeffected .in any suitable manner. electrical connections and arrangementof the filaments ma also be varied.

In'singleament lam s an efficient length of thin filament is usua 1yprovided by emtric lighting-current of constant or fairly 0on too Thelamp base The Y ploying a filament with a single coil and preventing itsdrooping by connecting the coil by an anchor with the mount; but withthe double-filament lamp an anchor to the large 17 in the elongated orpear-shaped bulb 11,

is likewise provided with a double helical coil, as most clearly shown,to obtain" the desired length of efficient thin filament and to reventit drooping into engagement with the arge filament.

1n the manufacture of the lamps the stem or support 20, to which thefilaments are attached, is provided in sealing the stem with a flattenedend, as shown, so that the extremeends of the filaments or the shortplatinum mounts therefor sealed in the end of the stem necessarily liein the same plane. By thus flattening the end of the lamp for sealingthis -'-L part may be conveniently manufactured by the machinery nowemployed for manufacturing ordinary lamps; but with a doublefilamentlamp the extreme ends of the filaments are necessarily brought intoclose relation near the flattened end of the stem. To give the maximumdistance between the legs of the filaments and insure that the legsshall diverge to prevent short-circuiting between them, the centralportions or coils of the filaments 17 and 18 are arranged at an angle toeach other and in different planes, preferably at a right angle to eachother, as shown in Figs. 1 and 2. This insures that the adjacent legs ofthe separate filaments shall diverge from one another outwardly from theend of the lamp-stem 20, so that there isFno or danger that they Willcome in contact. the same pur ose the coils of the separate filaments 17an 18 are twisted in opposite directionsthat is to say, one of the coilsis twisted toward the ri ht and the other to the left, as most clearlyshown in Fig. 1. By such an arrangement the separate legs of thefilaments diverge from the stem of the lamp in opposite directions.

The object of preventing short-circuiting by engagement between the legsof the fi'la ment may be attained either by arrangin the coils of theseparate filaments at an ang e to each other or by twistingthe coils inop 'osite directions, and while preferably bot ar-- rangements areemployed either one only would fall within the scope of the present invention.

The above-described mechanical arrangement of the filaments has beenfound effective in use with lighting-currents as high as one hundred andtwenty-five or one hundred Low-power filament 18, arranged above thehigh-power filament and thirty volts and may of course be satisfactorilyemployed with currents of-lower voltage.

' By employing two leading-in wires 23 and 24, twisted together toconnect the filaments,

instead'of a single connection to the joined 4 end of the filament, aspreviously employed, the manufacture of the lamp-stems by machineryinstead of by hand is greatly facilitated. Moreover, the wires 23 and 24are not twisted together or connected to the lamp-base until after thelamp has been pumped i. a, until after'the vacuum has been formed in theglass bulb. 11. While umping incandescent lamps. the filament iscircumstances, by passing a current through it, which by reason ofthe'so-called Edison efiect a :more perfect vacuum, is formed. 11npumpingmultifilament -la'm it has been found desirable in order that t e Edisoneffect shall be undisturbed: to pass-the current separate throughthefilaments, first through one and then through the other. By providingeachfilament with two leading-1n wires (four independent Wires for thetwo filaments in the present instance) the current may be readily passedthrough the filaments separately and. a more gerfec-t vacuum found thanwhen only three eading-in wires are provided for the two filaments, asin prior construction. After pumping, leading-in wires 23 and '24 aretwisted together'to connect the filaments and the proper connection madewith the lamp-base.

' Variations from the construction set forth may be readily made withoutdeparture from the essentials of the invention.

Having described my invention, What I claim as new, and desire to secureby Letters Patent, is- 1 Y 1; An electric incandescent lamp comprising asingle vacuum-bulb", a stem projecting Within said bulb and having aflattened end and two incandescent filaments,-the ends of which areattached to said stem in substantially the same plane, said filamentscomprising leg portions which diverge from said stem and centralportions arranged one above the other'and at an angle to each other indifferent planes.

2'. An electric incandescent lamp comprising a single vacuum-bulb,a'stem projecting saidfbu'lb and-having a flattened end and twoincandescent filaments, the ends of which are attached to said stem insubstantially the same plane, said filaments comprising leg portionswhich diverge-from said stem and central ortions formed into =coilsarranged one a 'ove the other and in different planes.

3. An electric incandescent lamp comprising a single vacuum-bulb, twofilaments supported within said bulb" with the centralportions of onesupported above that of the eated' to varying intensities, according toI other,-and a stem having a flattened end to which the ends of thefilaments are attached in substantially the same plane, the centralportions of said separate filaments being 5 formed into coils twlsted inopposite directions.

4. electric incandescent lamp comprising a single vacuum-bulb, twofilaments supported Within said bulb with the central porro tions of onesupported above that of the other, and a stem having a flattened end towhich the ends of the filaments are attached in substantially the sameplane, the central portions of said separate filaments being ormed intocoils twisted in opposite directions and arranged at angles to eachother and in different planes.

. WILLIAM J. PHELPS.

